/****************************************************************************
**
** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the QtQml module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial License Usage
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** accordance with the commercial license agreement provided with the
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** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
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** rights.  These rights are described in the Digia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
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****************************************************************************/

#include "qqmlimport_p.h"

#include <QtCore/qdebug.h>
#include <QtCore/qdir.h>
#include <QtQml/qqmlfile.h>
#include <QtCore/qfileinfo.h>
#include <QtCore/qpluginloader.h>
#include <QtCore/qlibraryinfo.h>
#include <QtCore/qreadwritelock.h>
#include <QtQml/qqmlextensioninterface.h>
#include <QtQml/qqmlextensionplugin.h>
#include <private/qqmlextensionplugin_p.h>
#include <private/qqmlglobal_p.h>
#include <private/qqmltypenamecache_p.h>
#include <private/qqmlengine_p.h>
#include <private/qfieldlist_p.h>

QT_BEGIN_NAMESPACE

DEFINE_BOOL_CONFIG_OPTION(qmlImportTrace, QML_IMPORT_TRACE)
DEFINE_BOOL_CONFIG_OPTION(qmlCheckTypes, QML_CHECK_TYPES)

static const QLatin1Char Dot('.');
static const QLatin1Char Slash('/');
static const QLatin1Char Backslash('\\');
static const QLatin1Char Colon(':');
static const QLatin1String Slash_qmldir("/qmldir");
static const QLatin1String String_qmldir("qmldir");
static const QString dotqml_string(QLatin1String(".qml"));

namespace {

QString resolveLocalUrl(const QString &url, const QString &relative)
{
    if (relative.contains(Colon)) {
        // contains a host name
        return QUrl(url).resolved(QUrl(relative)).toString();
    } else if (relative.isEmpty()) {
        return url;
    } else if (relative.at(0) == Slash || !url.contains(Slash)) {
        return relative;
    } else {
        QString base(url.left(url.lastIndexOf(Slash) + 1));

        if (relative == QLatin1String("."))
            return base;

        base.append(relative);

        // Remove any relative directory elements in the path
        int length = base.length();
        int index = 0;
        while ((index = base.indexOf(QLatin1String("/."), index)) != -1) {
            if ((length > (index + 2)) && (base.at(index + 2) == Dot) &&
                (length == (index + 3) || (base.at(index + 3) == Slash))) {
                // Either "/../" or "/..<END>"
                int previous = base.lastIndexOf(Slash, index - 1);
                if (previous == -1)
                    break;

                int removeLength = (index - previous) + 3;
                base.remove(previous + 1, removeLength);
                length -= removeLength;
                index = previous;
            } else if ((length == (index + 2)) || (base.at(index + 2) == Slash)) {
                // Either "/./" or "/.<END>"
                base.remove(index, 2);
                length -= 2;
            } else {
                ++index;
            }
        }

        return base;
    }
}

bool isPathAbsolute(const QString &path)
{
#if defined(Q_OS_UNIX)
    return (path.at(0) == Slash);
#else
    QFileInfo fi(path);
    return fi.isAbsolute();
#endif
}

// If the type does not already exist as a file import, add the type and return the new type
QQmlType *getTypeForUrl(const QString &urlString, const QHashedStringRef& typeName, QList<QQmlError> *errors)
{
    QUrl url(urlString);
    QQmlType *ret = QQmlMetaType::qmlType(url);
    if (!ret) { //QQmlType not yet existing for composite type
        int dot = typeName.indexOf(QLatin1Char('.'));
        QHashedStringRef unqualifiedtype = dot < 0 ? typeName : QHashedStringRef(typeName.constData() + dot + 1, typeName.length() - dot - 1);

        //XXX: The constData of the string ref is pointing somewhere unsafe in qmlregister, so we need to create a temporary copy
        QByteArray buf(unqualifiedtype.toUtf8().constData());

        QQmlPrivate::RegisterCompositeType reg = {
            url,
            "", //Empty URI indicates loaded via file imports
            -1,
            -1,
            buf.constData()
        };
        ret = QQmlMetaType::qmlTypeFromIndex(QQmlPrivate::qmlregister(QQmlPrivate::CompositeRegistration, &reg));
    }
    if (!ret) {//Usually when a type name is "found" but invalid
        //qDebug() << ret << urlString << QQmlMetaType::qmlType(url);
        if (!errors) // Cannot list errors properly, just quit
            qFatal("%s", QQmlMetaType::typeRegistrationFailures().join('\n').toLatin1().constData());
        QQmlError error;
        error.setDescription(QQmlMetaType::typeRegistrationFailures().join('\n'));
        errors->prepend(error);
    }
    return ret;

}

}

typedef QMap<QString, QString> StringStringMap;
Q_GLOBAL_STATIC(StringStringMap, qmlEnginePluginsWithRegisteredTypes); // stores the uri
void qmlClearEnginePlugins()
{
    foreach (const QString &s, qmlEnginePluginsWithRegisteredTypes()->values()) {
        QPluginLoader loader(s);
        loader.unload(); // ### Always returns false, worth doing?
    }
    qmlEnginePluginsWithRegisteredTypes()->clear();
}

class QQmlImportNamespace
{
public:
    QQmlImportNamespace() : nextNamespace(0) {}
    ~QQmlImportNamespace() { qDeleteAll(imports); }

    struct Import {
        QString uri;
        QString url;
        int majversion;
        int minversion;
        bool isLibrary;
        QQmlDirComponents qmlDirComponents;
        QQmlDirScripts qmlDirScripts;

        bool setQmldirContent(const QString &resolvedUrl, const QQmlTypeLoader::QmldirContent *qmldir,
                              QQmlImportNamespace *nameSpace, QList<QQmlError> *errors);

        static QQmlDirScripts getVersionedScripts(const QQmlDirScripts &qmldirscripts, int vmaj, int vmin);

        bool resolveType(QQmlTypeLoader *typeLoader, const QHashedStringRef &type,
                         int *vmajor, int *vminor, QQmlType** type_return,
                         QString *base = 0, bool *typeRecursionDetected = 0) const;
    };
    QList<Import *> imports;

    Import *findImport(const QString &uri);

    bool resolveType(QQmlTypeLoader *typeLoader, const QHashedStringRef& type,
                     int *vmajor, int *vminor, QQmlType** type_return,
                     QString *base = 0, QList<QQmlError> *errors = 0);

    // Prefix when used as a qualified import.  Otherwise empty.
    QHashedString prefix;

    // Used by QQmlImportsPrivate::qualifiedSets
    QQmlImportNamespace *nextNamespace;
};

class QQmlImportsPrivate
{
public:
    QQmlImportsPrivate(QQmlTypeLoader *loader);
    ~QQmlImportsPrivate();

    QQmlImportNamespace *importNamespace(const QString &prefix) const;

    bool addLibraryImport(const QString& uri, const QString &prefix,
                          int vmaj, int vmin, const QString &qmldirIdentifier, const QString &qmldirUrl, bool incomplete,
                          QQmlImportDatabase *database,
                          QList<QQmlError> *errors);

    bool addFileImport(const QString &uri, const QString &prefix,
                       int vmaj, int vmin,
                       bool isImplicitImport, bool incomplete, QQmlImportDatabase *database,
                       QList<QQmlError> *errors);

    bool updateQmldirContent(const QString &uri, const QString &prefix,
                             const QString &qmldirIdentifier, const QString& qmldirUrl,
                             QQmlImportDatabase *database,
                             QList<QQmlError> *errors);

    bool resolveType(const QHashedStringRef &type, int *vmajor, int *vminor,
                     QQmlType** type_return, QList<QQmlError> *errors);

    QUrl baseUrl;
    QString base;
    int ref;

    mutable QQmlImportNamespace unqualifiedset;

    QQmlImportNamespace *findQualifiedNamespace(const QHashedStringRef &) const;
    mutable QFieldList<QQmlImportNamespace, &QQmlImportNamespace::nextNamespace> qualifiedSets;

    QQmlTypeLoader *typeLoader;

    static bool locateQmldir(const QString &uri, int vmaj, int vmin,
                             QQmlImportDatabase *database,
                             QString *outQmldirFilePath, QString *outUrl);

    static bool validateQmldirVersion(const QQmlTypeLoader::QmldirContent *qmldir, const QString &uri, int vmaj, int vmin,
                                      QList<QQmlError> *errors);

    bool importExtension(const QString &absoluteFilePath, const QString &uri,
                         QQmlImportDatabase *database,
                         const QQmlTypeLoader::QmldirContent *qmldir,
                         QList<QQmlError> *errors);

    bool getQmldirContent(const QString &qmldirIdentifier, const QString &uri,
                          const QQmlTypeLoader::QmldirContent **qmldir, QList<QQmlError> *errors);

    QString resolvedUri(const QString &dir_arg, QQmlImportDatabase *database);

    QQmlImportNamespace::Import *addImportToNamespace(QQmlImportNamespace *nameSpace,
                                                      const QString &uri, const QString &url,
                                                      int vmaj, int vmin, QQmlScript::Import::Type type,
                                                      QList<QQmlError> *errors, bool lowPrecedence = false);
};

/*!
\class QQmlImports
\brief The QQmlImports class encapsulates one QML document's import statements.
\internal
*/
QQmlImports::QQmlImports(const QQmlImports &copy) 
: d(copy.d)
{
    ++d->ref;
}

QQmlImports &
QQmlImports::operator =(const QQmlImports &copy)
{
    ++copy.d->ref;
    if (--d->ref == 0)
        delete d;
    d = copy.d;
    return *this;
}

QQmlImports::QQmlImports(QQmlTypeLoader *typeLoader)
    : d(new QQmlImportsPrivate(typeLoader))
{
}

QQmlImports::~QQmlImports()
{
    if (--d->ref == 0)
        delete d;
}

/*!
  Sets the base URL to be used for all relative file imports added.
*/
void QQmlImports::setBaseUrl(const QUrl& url, const QString &urlString)
{
    d->baseUrl = url;

    if (urlString.isEmpty()) {
        d->base = url.toString();
    } else {
        //Q_ASSERT(url.toString() == urlString);
        d->base = urlString;
    }
}

/*!
  Returns the base URL to be used for all relative file imports added.
*/
QUrl QQmlImports::baseUrl() const
{
    return d->baseUrl;
}

void QQmlImports::populateCache(QQmlTypeNameCache *cache) const
{
    const QQmlImportNamespace &set = d->unqualifiedset;

    for (int ii = set.imports.count() - 1; ii >= 0; --ii) {
        const QQmlImportNamespace::Import *import = set.imports.at(ii);
        QQmlTypeModule *module = QQmlMetaType::typeModule(import->uri, import->majversion);
        if (module) {
            cache->m_anonymousImports.append(QQmlTypeModuleVersion(module, import->minversion));
        }
    }

    for (QQmlImportNamespace *ns = d->qualifiedSets.first(); ns; ns = d->qualifiedSets.next(ns)) {

        const QQmlImportNamespace &set = *ns;

        for (int ii = set.imports.count() - 1; ii >= 0; --ii) {
            const QQmlImportNamespace::Import *import = set.imports.at(ii);
            QQmlTypeModule *module = QQmlMetaType::typeModule(import->uri, import->majversion);
            if (module) {
                QQmlTypeNameCache::Import &typeimport = cache->m_namedImports[set.prefix];
                typeimport.modules.append(QQmlTypeModuleVersion(module, import->minversion));
            }
        }
    }
}

QList<QQmlImports::ScriptReference> QQmlImports::resolvedScripts() const
{
    QList<QQmlImports::ScriptReference> scripts;

    const QQmlImportNamespace &set = d->unqualifiedset;

    for (int ii = set.imports.count() - 1; ii >= 0; --ii) {
        const QQmlImportNamespace::Import *import = set.imports.at(ii);

        foreach (const QQmlDirParser::Script &script, import->qmlDirScripts) {
            ScriptReference ref;
            ref.nameSpace = script.nameSpace;
            ref.location = QUrl(import->url).resolved(QUrl(script.fileName));
            scripts.append(ref);
        }
    }

    for (QQmlImportNamespace *ns = d->qualifiedSets.first(); ns; ns = d->qualifiedSets.next(ns)) {
        const QQmlImportNamespace &set = *ns;

        for (int ii = set.imports.count() - 1; ii >= 0; --ii) {
            const QQmlImportNamespace::Import *import = set.imports.at(ii);

            foreach (const QQmlDirParser::Script &script, import->qmlDirScripts) {
                ScriptReference ref;
                ref.nameSpace = script.nameSpace;
                ref.qualifier = set.prefix;
                ref.location = QUrl(import->url).resolved(QUrl(script.fileName));
                scripts.append(ref);
            }
        }
    }

    return scripts;
}

/*!
    Form a complete path to a qmldir file, from a base URL, a module URI and version specification.
*/
QString QQmlImports::completeQmldirPath(const QString &uri, const QString &base, int vmaj, int vmin,
                                        ImportVersion version)
{
    QString url = uri;
    url.replace(Dot, Slash);

    QString dir = base;
    if (!dir.endsWith(Slash) && !dir.endsWith(Backslash))
        dir += Slash;
    dir += url;

    if (version == QQmlImports::FullyVersioned) {
        // extension with fully encoded version number (eg. MyModule.3.2)
        dir += QString(QLatin1String(".%1.%2")).arg(vmaj).arg(vmin);
    } else if (version == QQmlImports::PartiallyVersioned) {
        // extension with encoded version major (eg. MyModule.3)
        dir += QString(QLatin1String(".%1")).arg(vmaj);
    } // else extension without version number (eg. MyModule)

    return dir + Slash_qmldir;
}

/*!
  \internal

  The given (namespace qualified) \a type is resolved to either
  \list
  \li a QQmlImportNamespace stored at \a ns_return, or
  \li a QQmlType stored at \a type_return,
  \endlist

  If any return pointer is 0, the corresponding search is not done.

  \sa addFileImport(), addLibraryImport
*/
bool QQmlImports::resolveType(const QHashedStringRef &type,
                              QQmlType** type_return, int *vmaj, int *vmin,
                              QQmlImportNamespace** ns_return, QList<QQmlError> *errors) const
{
    QQmlImportNamespace* ns = d->findQualifiedNamespace(type);
    if (ns) {
        if (ns_return)
            *ns_return = ns;
        return true;
    }
    if (type_return) {
        if (d->resolveType(type,vmaj,vmin,type_return, errors)) {
            if (qmlImportTrace()) {
#define RESOLVE_TYPE_DEBUG qDebug().nospace() << "QQmlImports(" << qPrintable(baseUrl().toString()) \
                                              << ')' << "::resolveType: " << type.toString() << " => "

                if (type_return && *type_return && (*type_return)->isComposite())
                    RESOLVE_TYPE_DEBUG << (*type_return)->typeName() << ' ' << (*type_return)->sourceUrl() << " TYPE/URL";
                else if (type_return && *type_return)
                    RESOLVE_TYPE_DEBUG << (*type_return)->typeName() << " TYPE";
#undef RESOLVE_TYPE_DEBUG
            }
            return true;
        }
    }
    return false;
}

bool QQmlImportNamespace::Import::setQmldirContent(const QString &resolvedUrl, const QQmlTypeLoader::QmldirContent *qmldir, QQmlImportNamespace *nameSpace, QList<QQmlError> *errors)
{
    Q_ASSERT(resolvedUrl.endsWith(Slash));
    url = resolvedUrl;

    qmlDirComponents = qmldir->components();

    const QQmlDirScripts &scripts = qmldir->scripts();
    if (!scripts.isEmpty()) {
        // Verify that we haven't imported these scripts already
        for (QList<QQmlImportNamespace::Import *>::const_iterator it = nameSpace->imports.constBegin();
             it != nameSpace->imports.constEnd(); ++it) {
            if ((*it != this) && ((*it)->uri == uri)) {
                QQmlError error;
                error.setDescription(QQmlImportDatabase::tr("\"%1\" is ambiguous. Found in %2 and in %3").arg(uri).arg(url).arg((*it)->url));
                errors->prepend(error);
                return false;
            }
        }

        qmlDirScripts = getVersionedScripts(scripts, majversion, minversion);
    }

    return true;
}

QQmlDirScripts QQmlImportNamespace::Import::getVersionedScripts(const QQmlDirScripts &qmldirscripts, int vmaj, int vmin)
{
    QMap<QString, QQmlDirParser::Script> versioned;

    for (QList<QQmlDirParser::Script>::const_iterator sit = qmldirscripts.constBegin();
         sit != qmldirscripts.constEnd(); ++sit) {
        // Only include scripts that match our requested version
        if (((vmaj == -1) || (sit->majorVersion == vmaj)) &&
            ((vmin == -1) || (sit->minorVersion <= vmin))) {
            // Load the highest version that matches
            QMap<QString, QQmlDirParser::Script>::iterator vit = versioned.find(sit->nameSpace);
            if (vit == versioned.end() || (vit->minorVersion < sit->minorVersion)) {
                versioned.insert(sit->nameSpace, *sit);
            }
        }
    }

    return versioned.values();
}

/*!
  \internal

  Searching \e only in the namespace \a ns (previously returned in a call to
  resolveType(), \a type is found and returned to
  a QQmlType stored at \a type_return. If the type is from a QML file, the returned
  type will be a CompositeType.

  If the return pointer is 0, the corresponding search is not done.
*/
bool QQmlImports::resolveType(QQmlImportNamespace* ns, const QHashedStringRef &type,
                              QQmlType** type_return, int *vmaj, int *vmin) const
{
    return ns->resolveType(d->typeLoader,type,vmaj,vmin,type_return);
}

bool QQmlImportNamespace::Import::resolveType(QQmlTypeLoader *typeLoader,
                                              const QHashedStringRef& type, int *vmajor, int *vminor,
                                              QQmlType** type_return, QString *base, bool *typeRecursionDetected) const
{
    if (majversion >= 0 && minversion >= 0) {
        QQmlType *t = QQmlMetaType::qmlType(type, uri, majversion, minversion);
        if (t) {
            if (vmajor) *vmajor = majversion;
            if (vminor) *vminor = minversion;
            if (type_return)
                *type_return = t;
            return true;
        }
    }

    QQmlDirComponents::ConstIterator it = qmlDirComponents.find(type), end = qmlDirComponents.end();
    if (it != end) {
        QString componentUrl;
        QQmlDirComponents::ConstIterator candidate = end;
        for ( ; it != end && it.key() == type; ++it) {
            const QQmlDirParser::Component &c = *it;

            // importing version -1 means import ALL versions
            if ((majversion == -1) ||
                (c.majorVersion == majversion && c.minorVersion <= minversion)) {
                // Is this better than the previous candidate?
                if ((candidate == end) ||
                    (c.majorVersion > candidate->majorVersion) ||
                    ((c.majorVersion == candidate->majorVersion) && (c.minorVersion > candidate->minorVersion))) {
                    componentUrl = resolveLocalUrl(QString(url + c.typeName + dotqml_string), c.fileName);
                    if (c.internal && base) {
                        if (resolveLocalUrl(*base, c.fileName) != componentUrl)
                            continue; // failed attempt to access an internal type
                    }
                    if (base && (*base == componentUrl)) {
                        if (typeRecursionDetected)
                            *typeRecursionDetected = true;
                        continue; // no recursion
                    }

                    // This is our best candidate so far
                    candidate = it;
                }
            }
        }

        if (candidate != end) {
            if (type_return)
                *type_return = getTypeForUrl(componentUrl, type, 0);
            return (*type_return != 0);
        }
    } else if (!isLibrary) {
        QString qmlUrl = url + QString::fromRawData(type.constData(), type.length()) + dotqml_string;

        bool exists = false;

        if (QQmlFile::isBundle(qmlUrl)) {
            exists = QQmlFile::bundleFileExists(qmlUrl, typeLoader->engine());
        } else {
            exists = !typeLoader->absoluteFilePath(QQmlFile::urlToLocalFileOrQrc(qmlUrl)).isEmpty();
        }

        if (exists) {
            if (base && (*base == qmlUrl)) { // no recursion
                if (typeRecursionDetected)
                    *typeRecursionDetected = true;
            } else {
                if (type_return)
                    *type_return = getTypeForUrl(qmlUrl, type, 0);
                return (*type_return) != 0;
            }
        }
    }

    return false;
}

bool QQmlImportsPrivate::resolveType(const QHashedStringRef& type, int *vmajor, int *vminor,
                                     QQmlType** type_return, QList<QQmlError> *errors)
{
    QQmlImportNamespace *s = 0;
    int dot = type.indexOf(Dot);
    if (dot >= 0) {
        QHashedStringRef namespaceName(type.constData(), dot);
        s = findQualifiedNamespace(namespaceName);
        if (!s) {
            if (errors) {
                QQmlError error;
                error.setDescription(QQmlImportDatabase::tr("- %1 is not a namespace").arg(namespaceName.toString()));
                errors->prepend(error);
            }
            return false;
        }
        int ndot = type.indexOf(Dot,dot+1);
        if (ndot > 0) {
            if (errors) {
                QQmlError error;
                error.setDescription(QQmlImportDatabase::tr("- nested namespaces not allowed"));
                errors->prepend(error);
            }
            return false;
        }
    } else {
        s = &unqualifiedset;
    }
    QHashedStringRef unqualifiedtype = dot < 0 ? type : QHashedStringRef(type.constData()+dot+1, type.length()-dot-1);
    if (s) {
        if (s->resolveType(typeLoader,unqualifiedtype,vmajor,vminor,type_return, &base, errors))
            return true;
        if (s->imports.count() == 1 && !s->imports.at(0)->isLibrary && type_return && s != &unqualifiedset) {
            // qualified, and only 1 url
            *type_return = getTypeForUrl(resolveLocalUrl(s->imports.at(0)->url, unqualifiedtype.toString() + QLatin1String(".qml")), type, errors);
            return (*type_return != 0);
        }
    }

    return false;
}

QQmlImportNamespace::Import *QQmlImportNamespace::findImport(const QString &uri)
{
    for (QList<Import *>::iterator it = imports.begin(), end = imports.end(); it != end; ++it) {
        if ((*it)->uri == uri)
            return *it;
    }

    return 0;
}

bool QQmlImportNamespace::resolveType(QQmlTypeLoader *typeLoader, const QHashedStringRef &type,
                                      int *vmajor, int *vminor, QQmlType** type_return,
                                      QString *base, QList<QQmlError> *errors)
{
    bool typeRecursionDetected = false;
    for (int i=0; i<imports.count(); ++i) {
        const Import *import = imports.at(i);
        if (import->resolveType(typeLoader, type, vmajor, vminor, type_return,
                               base, &typeRecursionDetected)) {
            if (qmlCheckTypes()) {
                // check for type clashes
                for (int j = i+1; j<imports.count(); ++j) {
                    const Import *import2 = imports.at(j);
                    if (import2->resolveType(typeLoader, type, vmajor, vminor, 0, base)) {
                        if (errors) {
                            QString u1 = import->url;
                            QString u2 = import2->url;
                            if (base) {
                                QString b = *base;
                                int dot = b.lastIndexOf(Dot);
                                if (dot >= 0) {
                                    b = b.left(dot+1);
                                    QString l = b.left(dot);
                                    if (u1.startsWith(b))
                                        u1 = u1.mid(b.count());
                                    else if (u1 == l)
                                        u1 = QQmlImportDatabase::tr("local directory");
                                    if (u2.startsWith(b))
                                        u2 = u2.mid(b.count());
                                    else if (u2 == l)
                                        u2 = QQmlImportDatabase::tr("local directory");
                                }
                            }

                            QQmlError error;
                            if (u1 != u2) {
                                error.setDescription(QQmlImportDatabase::tr("is ambiguous. Found in %1 and in %2").arg(u1).arg(u2));
                            } else {
                                error.setDescription(QQmlImportDatabase::tr("is ambiguous. Found in %1 in version %2.%3 and %4.%5")
                                                        .arg(u1)
                                                        .arg(import->majversion).arg(import->minversion)
                                                        .arg(import2->majversion).arg(import2->minversion));
                            }
                            errors->prepend(error);
                        }
                        return false;
                    }
                }
            }
            return true;
        }
    }
    if (errors) {
        QQmlError error;
        if (typeRecursionDetected)
            error.setDescription(QQmlImportDatabase::tr("is instantiated recursively"));
        else
            error.setDescription(QQmlImportDatabase::tr("is not a type"));
        errors->prepend(error);
    }
    return false;
}

QQmlImportsPrivate::QQmlImportsPrivate(QQmlTypeLoader *loader)
: ref(1), typeLoader(loader) {
}

QQmlImportsPrivate::~QQmlImportsPrivate()
{
    while (QQmlImportNamespace *ns = qualifiedSets.takeFirst())
        delete ns;
}

QQmlImportNamespace *QQmlImportsPrivate::findQualifiedNamespace(const QHashedStringRef &prefix) const
{
    for (QQmlImportNamespace *ns = qualifiedSets.first(); ns; ns = qualifiedSets.next(ns)) {
        if (prefix == ns->prefix)
            return ns;
    }
    return 0;
}

/*!
Import an extension defined by a qmldir file.

\a qmldirFilePath is either a raw file path, or a bundle url.
*/
bool QQmlImportsPrivate::importExtension(const QString &qmldirFilePath,
                                         const QString &uri,
                                         QQmlImportDatabase *database,
                                         const QQmlTypeLoader::QmldirContent *qmldir,
                                         QList<QQmlError> *errors)
{
    Q_ASSERT(qmldir);

    if (qmlImportTrace())
        qDebug().nospace() << "QQmlImports(" << qPrintable(base) << ")::importExtension: "
                           << "loaded " << qmldirFilePath;

    if (!database->qmlDirFilesForWhichPluginsHaveBeenLoaded.contains(qmldirFilePath)) {

        QString qmldirPath = qmldirFilePath;

        int slash = qmldirPath.lastIndexOf(Slash);
        if (slash > 0)
            qmldirPath.truncate(slash);

        foreach (const QQmlDirParser::Plugin &plugin, qmldir->plugins()) {
            QString resolvedFilePath = database->resolvePlugin(typeLoader, qmldirPath,
                                                               plugin.path, plugin.name);
            if (!resolvedFilePath.isEmpty()) {
                if (!database->importPlugin(resolvedFilePath, uri, qmldir->typeNamespace(), errors)) {
                    if (errors) {
                        // XXX TODO: should we leave the import plugin error alone?
                        // Here, we pop it off the top and coalesce it into this error's message.
                        // The reason is that the lower level may add url and line/column numbering information.
                        QQmlError poppedError = errors->takeFirst();
                        QQmlError error;
                        error.setDescription(QQmlImportDatabase::tr("plugin cannot be loaded for module \"%1\": %2").arg(uri).arg(poppedError.description()));
                        error.setUrl(QUrl::fromLocalFile(qmldirFilePath));
                        errors->prepend(error);
                    }
                    return false;
                }
            } else {
                if (errors) {
                    QQmlError error;
                    error.setDescription(QQmlImportDatabase::tr("module \"%1\" plugin \"%2\" not found").arg(uri).arg(plugin.name));
                    error.setUrl(QUrl::fromLocalFile(qmldirFilePath));
                    errors->prepend(error);
                }
                return false;
            }
        }

        database->qmlDirFilesForWhichPluginsHaveBeenLoaded.insert(qmldirFilePath);
    }

    return true;
}

bool QQmlImportsPrivate::getQmldirContent(const QString &qmldirIdentifier, const QString &uri,
                                          const QQmlTypeLoader::QmldirContent **qmldir, QList<QQmlError> *errors)
{
    Q_ASSERT(errors);
    Q_ASSERT(qmldir);

    *qmldir = typeLoader->qmldirContent(qmldirIdentifier, uri);
    if (*qmldir) {
        // Ensure that parsing was successful
        if ((*qmldir)->hasError()) {
            QUrl url;

            if (QQmlFile::isBundle(qmldirIdentifier))
                url = QUrl(qmldirIdentifier);
            else
                url = QUrl::fromLocalFile(qmldirIdentifier);

            const QList<QQmlError> qmldirErrors = (*qmldir)->errors(uri);
            for (int i = 0; i < qmldirErrors.size(); ++i) {
                QQmlError error = qmldirErrors.at(i);
                error.setUrl(url);
                errors->append(error);
            }
            return false;
        }
    }

    return true;
}

QString QQmlImportsPrivate::resolvedUri(const QString &dir_arg, QQmlImportDatabase *database)
{
    struct I { static bool greaterThan(const QString &s1, const QString &s2) {
        return s1 > s2;
    } };

    QString dir = dir_arg;
    if (dir.endsWith(Slash) || dir.endsWith(Backslash))
        dir.chop(1);

    QStringList paths = database->fileImportPath;
    qSort(paths.begin(), paths.end(), I::greaterThan); // Ensure subdirs preceed their parents.

    QString stableRelativePath = dir;
    foreach(const QString &path, paths) {
        if (dir.startsWith(path)) {
            stableRelativePath = dir.mid(path.length()+1);
            break;
        }
    }

    stableRelativePath.replace(Backslash, Slash);

    // remove optional versioning in dot notation from uri
    int lastSlash = stableRelativePath.lastIndexOf(Slash);
    if (lastSlash >= 0) {
        int versionDot = stableRelativePath.indexOf(Dot, lastSlash);
        if (versionDot >= 0)
            stableRelativePath = stableRelativePath.left(versionDot);
    }

    stableRelativePath.replace(Slash, Dot);

    return stableRelativePath;
}

/*
Locates the qmldir file for \a uri version \a vmaj.vmin.  Returns true if found,
and fills in outQmldirFilePath and outQmldirUrl appropriately.  Otherwise returns
false.
*/
bool QQmlImportsPrivate::locateQmldir(const QString &uri, int vmaj, int vmin, QQmlImportDatabase *database,
                                      QString *outQmldirFilePath, QString *outQmldirPathUrl)
{
    Q_ASSERT(vmaj >= 0 && vmin >= 0); // Versions are always specified for libraries

    // Check cache first

    QQmlImportDatabase::QmldirCache *cacheHead = 0;
    {
    QQmlImportDatabase::QmldirCache **cachePtr = database->qmldirCache.value(uri);
    if (cachePtr) {
        cacheHead = *cachePtr;
        QQmlImportDatabase::QmldirCache *cache = cacheHead;
        while (cache) {
            if (cache->versionMajor == vmaj && cache->versionMinor == vmin) {
                *outQmldirFilePath = cache->qmldirFilePath;
                *outQmldirPathUrl = cache->qmldirPathUrl;
                return !cache->qmldirFilePath.isEmpty();
            }
            cache = cache->next;
        }
    }
    }

    QQmlTypeLoader &typeLoader = QQmlEnginePrivate::get(database->engine)->typeLoader;

    QStringList localImportPaths = database->importPathList(QQmlImportDatabase::Local);

    // Search local import paths for a matching version
    for (int version = QQmlImports::FullyVersioned; version <= QQmlImports::Unversioned; ++version) {
        foreach (const QString &path, localImportPaths) {
            QString qmldirPath = QQmlImports::completeQmldirPath(uri, path, vmaj, vmin, static_cast<QQmlImports::ImportVersion>(version));

            QString absoluteFilePath = typeLoader.absoluteFilePath(qmldirPath);
            if (!absoluteFilePath.isEmpty()) {
                QString url;
                QString absolutePath = absoluteFilePath.left(absoluteFilePath.lastIndexOf(Slash)+1);
                if (absolutePath.at(0) == Colon)
                    url = QLatin1String("qrc://") + absolutePath.mid(1);
                else
                    url = QUrl::fromLocalFile(absolutePath).toString();

                QQmlImportDatabase::QmldirCache *cache = new QQmlImportDatabase::QmldirCache;
                cache->versionMajor = vmaj;
                cache->versionMinor = vmin;
                cache->qmldirFilePath = absoluteFilePath;
                cache->qmldirPathUrl = url;
                cache->next = cacheHead;
                database->qmldirCache.insert(uri, cache);

                *outQmldirFilePath = absoluteFilePath;
                *outQmldirPathUrl = url;

                return true;
            }
        }
    }

    QQmlImportDatabase::QmldirCache *cache = new QQmlImportDatabase::QmldirCache;
    cache->versionMajor = vmaj;
    cache->versionMinor = vmin;
    cache->next = cacheHead;
    database->qmldirCache.insert(uri, cache);

    return false;
}

bool QQmlImportsPrivate::validateQmldirVersion(const QQmlTypeLoader::QmldirContent *qmldir, const QString &uri, int vmaj, int vmin,
                                               QList<QQmlError> *errors)
{
    int lowest_min = INT_MAX;
    int highest_min = INT_MIN;

    typedef QQmlDirComponents::const_iterator ConstIterator;
    const QQmlDirComponents &components = qmldir->components();

    ConstIterator cend = components.constEnd();
    for (ConstIterator cit = components.constBegin(); cit != cend; ++cit) {
        for (ConstIterator cit2 = components.constBegin(); cit2 != cit; ++cit2) {
            if ((cit2->typeName == cit->typeName) &&
                (cit2->majorVersion == cit->majorVersion) &&
                (cit2->minorVersion == cit->minorVersion)) {
                // This entry clashes with a predecessor
                QQmlError error;
                error.setDescription(QQmlImportDatabase::tr("\"%1\" version %2.%3 is defined more than once in module \"%4\"")
                                     .arg(cit->typeName).arg(cit->majorVersion).arg(cit->minorVersion).arg(uri));
                errors->prepend(error);
                return false;
            }
        }

        if (cit->majorVersion == vmaj) {
            lowest_min = qMin(lowest_min, cit->minorVersion);
            highest_min = qMax(highest_min, cit->minorVersion);
        }
    }

    typedef QList<QQmlDirParser::Script>::const_iterator SConstIterator;
    const QQmlDirScripts &scripts = qmldir->scripts();

    SConstIterator send = scripts.constEnd();
    for (SConstIterator sit = scripts.constBegin(); sit != send; ++sit) {
        for (SConstIterator sit2 = scripts.constBegin(); sit2 != sit; ++sit2) {
            if ((sit2->nameSpace == sit->nameSpace) &&
                (sit2->majorVersion == sit->majorVersion) &&
                (sit2->minorVersion == sit->minorVersion)) {
                // This entry clashes with a predecessor
                QQmlError error;
                error.setDescription(QQmlImportDatabase::tr("\"%1\" version %2.%3 is defined more than once in module \"%4\"")
                                     .arg(sit->nameSpace).arg(sit->majorVersion).arg(sit->minorVersion).arg(uri));
                errors->prepend(error);
                return false;
            }
        }

        if (sit->majorVersion == vmaj) {
            lowest_min = qMin(lowest_min, sit->minorVersion);
            highest_min = qMax(highest_min, sit->minorVersion);
        }
    }

    if (lowest_min > vmin || highest_min < vmin) {
        QQmlError error;
        error.setDescription(QQmlImportDatabase::tr("module \"%1\" version %2.%3 is not installed").arg(uri).arg(vmaj).arg(vmin));
        errors->prepend(error);
        return false;
    }

    return true;
}

QQmlImportNamespace *QQmlImportsPrivate::importNamespace(const QString &prefix) const
{
    QQmlImportNamespace *nameSpace = 0;

    if (prefix.isEmpty()) {
        nameSpace = &unqualifiedset;
    } else {
        nameSpace = findQualifiedNamespace(prefix);

        if (!nameSpace) {
            nameSpace = new QQmlImportNamespace;
            nameSpace->prefix = prefix;
            qualifiedSets.append(nameSpace);
        }
    }

    return nameSpace;
}

QQmlImportNamespace::Import *QQmlImportsPrivate::addImportToNamespace(QQmlImportNamespace *nameSpace,
                                                                      const QString &uri, const QString &url, int vmaj, int vmin,
                                                                      QQmlScript::Import::Type type,
                                                                      QList<QQmlError> *errors, bool lowPrecedence)
{
    Q_ASSERT(nameSpace);
    Q_ASSERT(errors);
    Q_UNUSED(errors);
    Q_ASSERT(url.isEmpty() || url.endsWith(Slash));

    QQmlImportNamespace::Import *import = new QQmlImportNamespace::Import;
    import->uri = uri;
    import->url = url;
    import->majversion = vmaj;
    import->minversion = vmin;
    import->isLibrary = (type == QQmlScript::Import::Library);

    if (lowPrecedence)
        nameSpace->imports.append(import);
    else
        nameSpace->imports.prepend(import);

    return import;
}

bool QQmlImportsPrivate::addLibraryImport(const QString& uri, const QString &prefix,
                                          int vmaj, int vmin, const QString &qmldirIdentifier, const QString &qmldirUrl, bool incomplete,
                                          QQmlImportDatabase *database,
                                          QList<QQmlError> *errors)
{
    Q_ASSERT(database);
    Q_ASSERT(errors);

    QQmlImportNamespace *nameSpace = importNamespace(prefix);
    Q_ASSERT(nameSpace);

    QQmlImportNamespace::Import *inserted = addImportToNamespace(nameSpace, uri, qmldirUrl, vmaj, vmin, QQmlScript::Import::Library, errors);
    Q_ASSERT(inserted);

    if (!incomplete) {
        const QQmlTypeLoader::QmldirContent *qmldir = 0;

        if (!qmldirIdentifier.isEmpty()) {
            if (!getQmldirContent(qmldirIdentifier, uri, &qmldir, errors))
                return false;

            if (qmldir) {
                if (!importExtension(qmldir->pluginLocation(), uri, database, qmldir, errors))
                    return false;

                if (!inserted->setQmldirContent(qmldirUrl, qmldir, nameSpace, errors))
                    return false;
            }
        }

        // Ensure that we are actually providing something
        if ((vmaj < 0) || (vmin < 0) || !QQmlMetaType::isModule(uri, vmaj, vmin)) {
            if (inserted->qmlDirComponents.isEmpty() && inserted->qmlDirScripts.isEmpty()) {
                QQmlError error;
                if (QQmlMetaType::isAnyModule(uri))
                    error.setDescription(QQmlImportDatabase::tr("module \"%1\" version %2.%3 is not installed").arg(uri).arg(vmaj).arg(vmin));
                else
                    error.setDescription(QQmlImportDatabase::tr("module \"%1\" is not installed").arg(uri));
                errors->prepend(error);
                return false;
            } else if ((vmaj >= 0) && (vmin >= 0) && qmldir) {
                // Verify that the qmldir content is valid for this version
                if (!validateQmldirVersion(qmldir, uri, vmaj, vmin, errors))
                    return false;
            }
        }
    }

    return true;
}

bool QQmlImportsPrivate::addFileImport(const QString& uri, const QString &prefix,
                                       int vmaj, int vmin,
                                       bool isImplicitImport, bool incomplete, QQmlImportDatabase *database,
                                       QList<QQmlError> *errors)
{
    Q_ASSERT(errors);

    QQmlImportNamespace *nameSpace = importNamespace(prefix);
    Q_ASSERT(nameSpace);

    // The uri for this import.  For library imports this is the same as uri
    // specified by the user, but it may be different in the case of file imports.
    QString importUri = uri;

    QString qmldirPath = importUri;
    if (importUri.endsWith(Slash))
        qmldirPath += String_qmldir;
    else
        qmldirPath += Slash_qmldir;

    QString qmldirUrl = resolveLocalUrl(base, qmldirPath);

    QString qmldirIdentifier;

    if (QQmlFile::isBundle(qmldirUrl)) {

        QString dir = resolveLocalUrl(base, importUri);
        Q_ASSERT(QQmlFile::isBundle(dir));
        if (!QQmlFile::bundleDirectoryExists(dir, typeLoader->engine())) {
            if (!isImplicitImport) {
                QQmlError error;
                error.setDescription(QQmlImportDatabase::tr("\"%1\": no such directory").arg(uri));
                error.setUrl(QUrl(qmldirUrl));
                errors->prepend(error);
            }
            return false;
        }

        // Transforms the (possible relative) uri into our best guess relative to the
        // import paths.
        importUri = resolvedUri(dir, database);
        if (importUri.endsWith(Slash))
            importUri.chop(1);

        if (QQmlFile::bundleFileExists(qmldirUrl, typeLoader->engine()))
            qmldirIdentifier = qmldirUrl;

    } else if (QQmlFile::isLocalFile(qmldirUrl)) {

        QString localFileOrQrc = QQmlFile::urlToLocalFileOrQrc(qmldirUrl);
        Q_ASSERT(!localFileOrQrc.isEmpty());

        QString dir = QQmlFile::urlToLocalFileOrQrc(resolveLocalUrl(base, importUri));
        if (!typeLoader->directoryExists(dir)) {
            if (!isImplicitImport) {
                QQmlError error;
                error.setDescription(QQmlImportDatabase::tr("\"%1\": no such directory").arg(uri));
                error.setUrl(QUrl(qmldirUrl));
                errors->prepend(error);
            }
            return false;
        }

        // Transforms the (possible relative) uri into our best guess relative to the
        // import paths.
        importUri = resolvedUri(dir, database);
        if (importUri.endsWith(Slash))
            importUri.chop(1);

        if (!typeLoader->absoluteFilePath(localFileOrQrc).isEmpty())
            qmldirIdentifier = localFileOrQrc;

    } else if (nameSpace->prefix.isEmpty() && !incomplete) {

        if (!isImplicitImport) {
            QQmlError error;
            error.setDescription(QQmlImportDatabase::tr("import \"%1\" has no qmldir and no namespace").arg(importUri));
            error.setUrl(QUrl(qmldirUrl));
            errors->prepend(error);
        }

        return false;

    }

    // The url for the path containing files for this import
    QString url = resolveLocalUrl(base, uri);
    if (!url.endsWith(Slash) && !url.endsWith(Backslash))
        url += Slash;

    QQmlImportNamespace::Import *inserted = addImportToNamespace(nameSpace, importUri, url, vmaj, vmin, QQmlScript::Import::File, errors, isImplicitImport);
    Q_ASSERT(inserted);

    if (!incomplete && !qmldirIdentifier.isEmpty()) {
        const QQmlTypeLoader::QmldirContent *qmldir = 0;
        if (!getQmldirContent(qmldirIdentifier, importUri, &qmldir, errors))
            return false;

        if (qmldir) {
            if (!importExtension(qmldir->pluginLocation(), importUri, database, qmldir, errors))
                return false;

            if (!inserted->setQmldirContent(url, qmldir, nameSpace, errors))
                return false;
        }
    }

    return true;
}

bool QQmlImportsPrivate::updateQmldirContent(const QString &uri, const QString &prefix,
                                             const QString &qmldirIdentifier, const QString& qmldirUrl,
                                             QQmlImportDatabase *database, QList<QQmlError> *errors)
{
    QQmlImportNamespace *nameSpace = importNamespace(prefix);
    Q_ASSERT(nameSpace);

    if (QQmlImportNamespace::Import *import = nameSpace->findImport(uri)) {
        const QQmlTypeLoader::QmldirContent *qmldir = 0;
        if (!getQmldirContent(qmldirIdentifier, uri, &qmldir, errors))
            return false;

        if (qmldir) {
            if (!importExtension(qmldir->pluginLocation(), uri, database, qmldir, errors))
                return false;

            if (import->setQmldirContent(qmldirUrl, qmldir, nameSpace, errors)) {
                // Ensure that we are actually providing something
                int vmaj = import->majversion;
                int vmin = import->minversion;

                if (import->qmlDirComponents.isEmpty() && import->qmlDirScripts.isEmpty()) {
                    // The implicit import qmldir can be empty
                    if (uri != QLatin1String(".")) {
                        QQmlError error;
                        if (QQmlMetaType::isAnyModule(uri))
                            error.setDescription(QQmlImportDatabase::tr("module \"%1\" version %2.%3 is not installed").arg(uri).arg(vmaj).arg(vmin));
                        else
                            error.setDescription(QQmlImportDatabase::tr("module \"%1\" is not installed").arg(uri));
                        errors->prepend(error);
                        return false;
                    }
                } else if ((vmaj >= 0) && (vmin >= 0)) {
                    // Verify that the qmldir content is valid for this version
                    if (!validateQmldirVersion(qmldir, uri, vmaj, vmin, errors))
                        return false;
                }
                return true;
            }
        }
    }

    if (errors->isEmpty()) {
        QQmlError error;
        error.setDescription(QQmlTypeLoader::tr("Cannot update qmldir content for '%1'").arg(uri));
        errors->prepend(error);
    }

    return false;
}

/*!
  \internal

  Adds an implicit "." file import.  This is equivalent to calling addFileImport(), but error
  messages related to the path or qmldir file not existing are suppressed.

  Additionally, this will add the import with lowest instead of highest precedence.
*/
bool QQmlImports::addImplicitImport(QQmlImportDatabase *importDb, QList<QQmlError> *errors)
{
    Q_ASSERT(errors);

    if (qmlImportTrace())
        qDebug().nospace() << "QQmlImports(" << qPrintable(baseUrl().toString())
                           << ")::addImplicitImport";

    bool incomplete = !isLocal(baseUrl());
    return d->addFileImport(QLatin1String("."), QString(), -1, -1, true, incomplete, importDb, errors);
}

/*!
  \internal

  Adds information to \a imports such that subsequent calls to resolveType()
  will resolve types qualified by \a prefix by considering types found at the given \a uri.

  The uri is either a directory (if importType is FileImport), or a URI resolved using paths
  added via addImportPath() (if importType is LibraryImport).

  The \a prefix may be empty, in which case the import location is considered for
  unqualified types.

  The base URL must already have been set with Import::setBaseUrl().

  Optionally, the url the import resolved to can be returned by providing the url parameter.
  Not all imports will result in an output url being generated, in which case the url will
  be set to an empty string.

  Returns true on success, and false on failure.  In case of failure, the errors array will
  filled appropriately.
*/
bool QQmlImports::addFileImport(QQmlImportDatabase *importDb,
                                const QString& uri, const QString& prefix, int vmaj, int vmin,
                                bool incomplete, QList<QQmlError> *errors)
{
    Q_ASSERT(importDb);
    Q_ASSERT(errors);

    if (qmlImportTrace())
        qDebug().nospace() << "QQmlImports(" << qPrintable(baseUrl().toString()) << ')' << "::addFileImport: "
                           << uri << ' ' << vmaj << '.' << vmin << " as " << prefix;

    return d->addFileImport(uri, prefix, vmaj, vmin, false, incomplete, importDb, errors);
}

bool QQmlImports::addLibraryImport(QQmlImportDatabase *importDb,
                                   const QString &uri, const QString &prefix, int vmaj, int vmin,
                                   const QString &qmldirIdentifier, const QString& qmldirUrl, bool incomplete, QList<QQmlError> *errors)
{
    Q_ASSERT(importDb);
    Q_ASSERT(errors);

    if (qmlImportTrace())
        qDebug().nospace() << "QQmlImports(" << qPrintable(baseUrl().toString()) << ')' << "::addLibraryImport: "
                           << uri << ' ' << vmaj << '.' << vmin << " as " << prefix;

    return d->addLibraryImport(uri, prefix, vmaj, vmin, qmldirIdentifier, qmldirUrl, incomplete, importDb, errors);
}

bool QQmlImports::updateQmldirContent(QQmlImportDatabase *importDb,
                                      const QString &uri, const QString &prefix,
                                      const QString &qmldirIdentifier, const QString& qmldirUrl, QList<QQmlError> *errors)
{
    Q_ASSERT(importDb);
    Q_ASSERT(errors);

    if (qmlImportTrace())
        qDebug().nospace() << "QQmlImports(" << qPrintable(baseUrl().toString()) << ')' << "::updateQmldirContent: "
                           << uri << " to " << qmldirUrl << " as " << prefix;

    return d->updateQmldirContent(uri, prefix, qmldirIdentifier, qmldirUrl, importDb, errors);
}

bool QQmlImports::locateQmldir(QQmlImportDatabase *importDb,
                               const QString& uri, int vmaj, int vmin,
                               QString *qmldirFilePath, QString *url)
{
    return d->locateQmldir(uri, vmaj, vmin, importDb, qmldirFilePath, url);
}

bool QQmlImports::isLocal(const QString &url)
{
    return QQmlFile::isBundle(url) || !QQmlFile::urlToLocalFileOrQrc(url).isEmpty();
}

bool QQmlImports::isLocal(const QUrl &url)
{
    return QQmlFile::isBundle(url) || !QQmlFile::urlToLocalFileOrQrc(url).isEmpty();
}


/*!
\class QQmlImportDatabase
\brief The QQmlImportDatabase class manages the QML imports for a QQmlEngine.
\internal
*/
QQmlImportDatabase::QQmlImportDatabase(QQmlEngine *e)
: engine(e)
{
    filePluginPath << QLatin1String(".");

    // Search order is applicationDirPath(), $QML2_IMPORT_PATH, QLibraryInfo::Qml2ImportsPath

    QString installImportsPath =  QLibraryInfo::location(QLibraryInfo::Qml2ImportsPath);
    addImportPath(installImportsPath);

    // env import paths
    QByteArray envImportPath = qgetenv("QML2_IMPORT_PATH");
    if (!envImportPath.isEmpty()) {
#if defined(Q_OS_WIN)
        QLatin1Char pathSep(';');
#else
        QLatin1Char pathSep(':');
#endif
        QStringList paths = QString::fromLatin1(envImportPath).split(pathSep, QString::SkipEmptyParts);
        for (int ii = paths.count() - 1; ii >= 0; --ii)
            addImportPath(paths.at(ii));
    }

    addImportPath(QCoreApplication::applicationDirPath());
}

QQmlImportDatabase::~QQmlImportDatabase()
{
    qDeleteAll(qmldirCache);
    qmldirCache.clear();
}

/*!
  \internal

  Returns the result of the merge of \a baseName with \a path, \a suffixes, and \a prefix.
  The \a prefix must contain the dot.

  \a qmldirPath is the location of the qmldir file.
 */
QString QQmlImportDatabase::resolvePlugin(QQmlTypeLoader *typeLoader,
                                          const QString &qmldirPath,
                                          const QString &qmldirPluginPath,
                                          const QString &baseName, const QStringList &suffixes,
                                          const QString &prefix)
{
    QStringList searchPaths = filePluginPath;
    bool qmldirPluginPathIsRelative = QDir::isRelativePath(qmldirPluginPath);
    if (!qmldirPluginPathIsRelative)
        searchPaths.prepend(qmldirPluginPath);

    foreach (const QString &pluginPath, searchPaths) {

        QString resolvedPath;
        if (pluginPath == QLatin1String(".")) {
            if (qmldirPluginPathIsRelative && !qmldirPluginPath.isEmpty() && qmldirPluginPath != QLatin1String("."))
                resolvedPath = QDir::cleanPath(qmldirPath + Slash + qmldirPluginPath);
            else
                resolvedPath = qmldirPath;
        } else {
            if (QDir::isRelativePath(pluginPath))
                resolvedPath = QDir::cleanPath(qmldirPath + Slash + pluginPath);
            else
                resolvedPath = pluginPath;
        }

        // hack for resources, should probably go away
        if (resolvedPath.startsWith(Colon))
            resolvedPath = QCoreApplication::applicationDirPath();

        if (!resolvedPath.endsWith(Slash))
            resolvedPath += Slash;

        foreach (const QString &suffix, suffixes) {
            QString pluginFileName = prefix;

            pluginFileName += baseName;
            pluginFileName += suffix;

            QString absolutePath = typeLoader->absoluteFilePath(resolvedPath + pluginFileName);
            if (!absolutePath.isEmpty())
                return absolutePath;
        }
    }

    if (qmlImportTrace())
        qDebug() << "QQmlImportDatabase::resolvePlugin: Could not resolve plugin" << baseName 
                 << "in" << qmldirPath;

    return QString();
}

/*!
  \internal

  Returns the result of the merge of \a baseName with \a dir and the platform suffix.

  \table
  \header \li Platform \li Valid suffixes
  \row \li Windows     \li \c .dll
  \row \li Unix/Linux  \li \c .so
  \row \li AIX  \li \c .a
  \row \li HP-UX       \li \c .sl, \c .so (HP-UXi)
  \row \li Mac OS X    \li \c .dylib, \c .bundle, \c .so
  \endtable

  Version number on unix are ignored.
*/
QString QQmlImportDatabase::resolvePlugin(QQmlTypeLoader *typeLoader,
                                                  const QString &qmldirPath, const QString &qmldirPluginPath,
                                                  const QString &baseName)
{
#if defined(Q_OS_WIN32) || defined(Q_OS_WINCE)
    return resolvePlugin(typeLoader, qmldirPath, qmldirPluginPath, baseName,
                         QStringList()
# ifdef QT_DEBUG
                         << QLatin1String("d.dll") // try a qmake-style debug build first
# endif
                         << QLatin1String(".dll"));
#else

# if defined(Q_OS_DARWIN)

    return resolvePlugin(typeLoader, qmldirPath, qmldirPluginPath, baseName,
                         QStringList()
# ifdef QT_DEBUG
                         << QLatin1String("_debug.dylib") // try a qmake-style debug build first
                         << QLatin1String(".dylib")
# else
                         << QLatin1String(".dylib")
                         << QLatin1String("_debug.dylib") // try a qmake-style debug build after
# endif
                         << QLatin1String(".so")
                         << QLatin1String(".bundle"),
                         QLatin1String("lib"));
# else  // Generic Unix
    QStringList validSuffixList;

#  if defined(Q_OS_HPUX)
/*
    See "HP-UX Linker and Libraries User's Guide", section "Link-time Differences between PA-RISC and IPF":
    "In PA-RISC (PA-32 and PA-64) shared libraries are suffixed with .sl. In IPF (32-bit and 64-bit),
    the shared libraries are suffixed with .so. For compatibility, the IPF linker also supports the .sl suffix."
 */
    validSuffixList << QLatin1String(".sl");
#   if defined __ia64
    validSuffixList << QLatin1String(".so");
#   endif
#  elif defined(Q_OS_AIX)
    validSuffixList << QLatin1String(".a") << QLatin1String(".so");
#  elif defined(Q_OS_UNIX)
    validSuffixList << QLatin1String(".so");
#  endif

    // Examples of valid library names:
    //  libfoo.so

    return resolvePlugin(typeLoader, qmldirPath, qmldirPluginPath, baseName, validSuffixList, QLatin1String("lib"));
# endif

#endif
}

/*!
    \internal
*/
QStringList QQmlImportDatabase::pluginPathList() const
{
    return filePluginPath;
}

/*!
    \internal
*/
void QQmlImportDatabase::setPluginPathList(const QStringList &paths)
{
    if (qmlImportTrace())
        qDebug().nospace() << "QQmlImportDatabase::setPluginPathList: " << paths;

    filePluginPath = paths;
}

/*!
    \internal
*/
void QQmlImportDatabase::addPluginPath(const QString& path)
{
    if (qmlImportTrace())
        qDebug().nospace() << "QQmlImportDatabase::addPluginPath: " << path;

    QUrl url = QUrl(path);
    if (url.isRelative() || url.scheme() == QLatin1String("file")
            || (url.scheme().length() == 1 && QFile::exists(path)) ) {  // windows path
        QDir dir = QDir(path);
        filePluginPath.prepend(dir.canonicalPath());
    } else {
        filePluginPath.prepend(path);
    }
}

/*!
    \internal
*/
void QQmlImportDatabase::addImportPath(const QString& path)
{
    if (qmlImportTrace())
        qDebug().nospace() << "QQmlImportDatabase::addImportPath: " << path;

    if (path.isEmpty())
        return;

    QUrl url = QUrl(path);
    QString cPath;

    if (url.scheme() == QLatin1String("file")) {
        cPath = QQmlFile::urlToLocalFileOrQrc(url);
    } else if (path.startsWith(QLatin1Char(':'))) {
        // qrc directory, e.g. :/foo
        // need to convert to a qrc url, e.g. qrc:/foo
        cPath = QStringLiteral("qrc") + path;
        cPath.replace(Backslash, Slash);
    } else if (url.isRelative() ||
               (url.scheme().length() == 1 && QFile::exists(path)) ) {  // windows path
        QDir dir = QDir(path);
        cPath = dir.canonicalPath();
    } else {
        cPath = path;
        cPath.replace(Backslash, Slash);
    }

    if (!cPath.isEmpty()
        && !fileImportPath.contains(cPath))
        fileImportPath.prepend(cPath);
}

/*!
    \internal
*/
QStringList QQmlImportDatabase::importPathList(PathType type) const
{
    if (type == LocalOrRemote)
        return fileImportPath;

    QStringList list;
    foreach (const QString &path, fileImportPath) {
        bool localPath = isPathAbsolute(path) || QQmlFile::isLocalFile(path);
        if (localPath == (type == Local))
            list.append(path);
    }

    return list;
}

/*!
    \internal
*/
void QQmlImportDatabase::setImportPathList(const QStringList &paths)
{
    if (qmlImportTrace())
        qDebug().nospace() << "QQmlImportDatabase::setImportPathList: " << paths;

    fileImportPath = paths;

    // Our existing cached paths may have been invalidated
    qmldirCache.clear();
}

/*!
    \internal
*/
bool QQmlImportDatabase::importPlugin(const QString &filePath, const QString &uri, const QString &typeNamespace, QList<QQmlError> *errors)
{
    if (qmlImportTrace())
        qDebug().nospace() << "QQmlImportDatabase::importPlugin: " << uri << " from " << filePath;

#ifndef QT_NO_LIBRARY
    QFileInfo fileInfo(filePath);
    const QString absoluteFilePath = fileInfo.absoluteFilePath();

    bool engineInitialized = initializedPlugins.contains(absoluteFilePath);
    bool typesRegistered = qmlEnginePluginsWithRegisteredTypes()->contains(absoluteFilePath);

    if (typesRegistered) {
        Q_ASSERT_X(qmlEnginePluginsWithRegisteredTypes()->value(absoluteFilePath) == uri,
                   "QQmlImportDatabase::importPlugin",
                   "Internal error: Plugin imported previously with different uri");
    }

    if (!engineInitialized || !typesRegistered) {
        if (!QQml_isFileCaseCorrect(absoluteFilePath)) {
            if (errors) {
                QQmlError error;
                error.setDescription(tr("File name case mismatch for \"%1\"").arg(absoluteFilePath));
                errors->prepend(error);
            }
            return false;
        }
        QPluginLoader loader(absoluteFilePath);

        if (!loader.load()) {
            if (errors) {
                QQmlError error;
                error.setDescription(loader.errorString());
                errors->prepend(error);
            }
            return false;
        }

        QObject *instance = loader.instance();
        if (QQmlTypesExtensionInterface *iface = qobject_cast<QQmlExtensionInterface *>(instance)) {

            const QByteArray bytes = uri.toUtf8();
            const char *moduleId = bytes.constData();
            if (!typesRegistered) {

                qmlEnginePluginsWithRegisteredTypes()->insert(absoluteFilePath, uri);

                QStringList registrationFailures;

                {
                    QWriteLocker lock(QQmlMetaType::typeRegistrationLock());

                    if (!typeNamespace.isEmpty()) {
                        // This is an 'identified' module
                        if (typeNamespace != uri) {
                            // The namespace for type registrations must match the URI for locating the module
                            QQmlError error;
                            error.setDescription(tr("Module namespace '%1' does not match import URI '%2'").arg(typeNamespace).arg(uri));
                            errors->prepend(error);
                            return false;
                        }

                        if (QQmlMetaType::namespaceContainsRegistrations(typeNamespace)) {
                            // Other modules have already installed to this namespace
                            QQmlError error;
                            error.setDescription(tr("Namespace '%1' has already been used for type registration").arg(typeNamespace));
                            errors->prepend(error);
                            return false;
                        } else {
                            QQmlMetaType::protectNamespace(typeNamespace);
                        }
                    } else {
                        // This is not an identified module - provide a warning
                        qWarning().nospace() << qPrintable(tr("Module '%1' does not contain a module identifier directive - it cannot be protected from external registrations.").arg(uri));
                    }

                    QQmlMetaType::setTypeRegistrationNamespace(typeNamespace);

                    if (QQmlExtensionPlugin *plugin = qobject_cast<QQmlExtensionPlugin *>(instance)) {
                        // Set the directory, not the library file itself
                        QQmlExtensionPluginPrivate::get(plugin)->baseUrl = QUrl::fromLocalFile(fileInfo.absolutePath());
                    }
                    iface->registerTypes(moduleId);

                    registrationFailures = QQmlMetaType::typeRegistrationFailures();
                    QQmlMetaType::setTypeRegistrationNamespace(QString());
                }

                if (!registrationFailures.isEmpty()) {
                    foreach (const QString &failure, registrationFailures) {
                        QQmlError error;
                        error.setDescription(failure);
                        errors->prepend(error);
                    }
                    return false;
                }
            }
            if (!engineInitialized) {
                // things on the engine (eg. adding new global objects) have to be done for every 
                // engine.  
                // XXX protect against double initialization
                initializedPlugins.insert(absoluteFilePath);

                QQmlExtensionInterface *eiface = 
                    qobject_cast<QQmlExtensionInterface *>(instance);
                if (eiface) {
                    QQmlEnginePrivate *ep = QQmlEnginePrivate::get(engine);
                    ep->typeLoader.initializeEngine(eiface, moduleId);
                }
            }
        } else {
            if (errors) {
                QQmlError error;
                error.setDescription(loader.errorString());
                errors->prepend(error);
            }
            return false;
        }
    }

    return true;
#else
    return false;
#endif
}

QT_END_NAMESPACE
